CVE-1999-0351
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedFTP PASV "Pizza Thief" denial of service and unauthorized data access. Attackers can steal data by connecting to a port that was intended for use by a client.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThis is a historical vulnerability in FTP server implementations where the PASV command returns a random high port for data transfers, allowing an attacker to intercept connections to that port before the legitimate client. This enables unauthorized data access (stealing file transfers) and denial of service by occupying ports intended for client data connections.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE dataall versionsCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- None
- Availability
- Partial
AV:N/AC:L/Au:N/C:P/I:N/A:P
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify if FTP server with PASV support is runningScan the network for port 21 (FTP control port) and identify the FTP server software version using banner grabbing or network scanning toolsAffected if An FTP server is accessible on the network and responds to FTP commands
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Confirm PASV mode is enabledConnect to the FTP server and issue the PASV command; observe the response for a high port number (typically in range 1024-65535)Affected if The server responds to PASV with a port address for data transfer
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Verify data port accessibility from untrusted networksAttempt to connect to the high port returned by PASV from an external or untrusted network segmentAffected if The data port is reachable from networks other than the intended client network
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Check for port predictabilityIssue multiple PASV commands and compare the returned port numbers to determine if they are predictable or follow a patternAffected if The returned ports are predictable or follow a sequential pattern rather than being truly random
A user is affected if they run an FTP server with PASV mode enabled and the data transfer ports are accessible from untrusted network locations.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataDisable unencrypted FTP and use SFTP/FTPS instead; if legacy FTP is required, implement port validation and ensure data connection ports are not predictable or accessible to unauthorized parties.
- Consultation1.0 h
- Implementation2.0 h
- Testing1.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-1999-0351 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-1999-0351 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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